全文获取类型
收费全文 | 1630篇 |
免费 | 293篇 |
国内免费 | 143篇 |
专业分类
化学 | 1022篇 |
晶体学 | 9篇 |
力学 | 86篇 |
综合类 | 28篇 |
数学 | 215篇 |
物理学 | 706篇 |
出版年
2024年 | 4篇 |
2023年 | 32篇 |
2022年 | 44篇 |
2021年 | 46篇 |
2020年 | 61篇 |
2019年 | 65篇 |
2018年 | 54篇 |
2017年 | 36篇 |
2016年 | 69篇 |
2015年 | 65篇 |
2014年 | 79篇 |
2013年 | 106篇 |
2012年 | 127篇 |
2011年 | 144篇 |
2010年 | 81篇 |
2009年 | 89篇 |
2008年 | 83篇 |
2007年 | 92篇 |
2006年 | 93篇 |
2005年 | 78篇 |
2004年 | 76篇 |
2003年 | 49篇 |
2002年 | 49篇 |
2001年 | 27篇 |
2000年 | 27篇 |
1999年 | 40篇 |
1998年 | 35篇 |
1997年 | 25篇 |
1996年 | 37篇 |
1995年 | 29篇 |
1994年 | 27篇 |
1993年 | 26篇 |
1992年 | 24篇 |
1991年 | 23篇 |
1990年 | 19篇 |
1989年 | 25篇 |
1988年 | 21篇 |
1987年 | 12篇 |
1986年 | 9篇 |
1985年 | 8篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1976年 | 4篇 |
1973年 | 4篇 |
1930年 | 1篇 |
排序方式: 共有2066条查询结果,搜索用时 0 毫秒
41.
利用准经典轨线理论 ,在BW 2和G3两个势能面上 ,研究了Cl +HD反应的动力学 .计算结果表明 ,产物的转动取向对势能面及反应体系的质量因子非常敏感 .在BW 2势能面上 ,计算的两个产物的转动取向强于在G3势能面上计算的结果 ,而无论是在BW 2势能面上还是在G3势能面上 ,DCl产物的取向都强于HCl产物的取向 .计算结果还表明 ,在不同的势能面上反应物的转动激发对反应的影响有着显著的不同 .在BW 2势能面上 ,反应物的初始转动激发有利于Cl+HD反应的进行 ;而在G3势能面上 ,反应物的初始转动激发消弱了反应的反应性 相似文献
42.
Effects of pulse chirp on supercontinuum produced in dispersion decreasing fibre 总被引:1,自引:0,他引:1 下载免费PDF全文
The supercontinuum (SC) source plays a key role in wavelength division multiplexing over the optical time division multiplexing (WDM/OTDM) transmission system. The SC produced in dispersion decreasing fibre (DDF) is wider and flatter than that produced in dispersion shifted fibre (DSF). In this paper, a SC producing process in DDF is numerically simulated, the effects of pump pulse chirp on the SC width and flatness are initially studied and the corresponding theoretical explanations are given. Particularly, we have analysed and compared the evolutions of the SC along DDF pumped by different chirp pulses. Several valuable conclusions are obtained. 相似文献
43.
44.
45.
46.
47.
采用紫外光电子能谱,研究了新型有机发光材料八芳基环辛四烯(OPCOT)在金属Ru(0001)表面上的电子结构,以及它们之间的相互作用.位于费米能级以下43,69,93和114eV处的4个谱峰分别来自于OPCOT材料中苯环的πCC,σCC,σCH和σHH轨道,位于30eV处的谱峰反映了8个苯环聚合后具有π轨道特性的C—C键.OPCOT材料的价带顶位于费米能级以下25eV处,OPCOT材料在Ru(0001)表面上的功函数为395eV.150℃以下,OPCOT材料可以在Ru(0001)表面稳定存在.随温度的升高,OPCOT材料主要以脱附的形式减少
关键词:
八芳基环辛四烯
光电子能谱
价电子结构
脱附 相似文献
48.
We report an effect of enhanced emission of laser generated plume in gas ambi-ent.Nonreactive argon gas was used in the experiment of UV laser ablation of copper plate.The emission of Cu atoms from the plume was increased more than the times.The emission in-tensity is sensitive to the gas pressure,but in a certain region of gas pressure,the enhanced ef-fect can be controlled stably.For the emission lines from other element,Zn,in the plume,the intensities are subjected to the same factor of increasement. 相似文献
49.
Community detection has become an important methodology to understand the organization and function of various real-world networks. The label propagation algorithm (LPA) is an almost linear time algorithm proved to be effective in finding a good community structure. However, LPA has a limitation caused by its one-hop horizon. Specifically, each node in LPA adopts the label shared by most of its one-hop neighbors; much network topology information is lost in this process, which we believe is one of the main reasons for its instability and poor performance. Therefore in this paper we introduce a measure named weighted coherent neighborhood propinquity (weighted-CNP) to represent the probability that a pair of vertices are involved in the same community. In label update, a node adopts the label that has the maximum weighted-CNP instead of the one that is shared by most of its neighbors. We propose a dynamic and adaptive weighted-CNP called entropic-CNP by using the principal of entropy to modulate the weights. Furthermore, we propose a framework to integrate the weighted-CNP in other algorithms in detecting community structure. We test our algorithm on both computer-generated networks and real-world networks. The experimental results show that our algorithm is more robust and effective than LPA in large-scale networks. 相似文献
50.
Sen-yue Lou Ji Lin Xiao-yan Tang 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,22(4):473-478
The Painlevé integrability of the 2+1 dimensional AKNS system is proved. Using the standard truncated Painlevé expansion which
corresponds to a special B?cklund transformation, some special types of the localized excitations like the solitoff solutions,
multi-dromion solutions and multi-ring soliton solutions are obtained.
Received 31 January 2001 and Received in final form 15 May 2001 相似文献